Thimphu is situated in the compressed, linear valley of the Raidak River,also called the Thimphu River (Thimpu Chuu). It is surrounded by the hills which are in the altitudinal range of 2,000–3,800 metres (6,600–12,500 ft) warm temperate climate exists between 2,000–3,000 metres (6,600–9,800 ft) and cold temperate zone between 3,000–3,800 metres (9,800–12,500 ft)), the city itself has an altitude range varying between 2,248 metres (7,375 ft) and 2,648 metres (8,688 ft). Nevertheless these two variations in altitude and climate establish the habitable zones and vegetation typology for the valley. The valley is thinly-forested and is spread out to the north and west. At the southern end of the city, the Lungten Zampa bridge connects the east and west banks of the Wang Chuu which flows through the heart of city.
The Raidak River rises in the snow fields at an altitude of about 7,000 metres (23,000 ft),with many tributaries flowing from the Himalayan peaks that chiefly dominate the topography of the Thimphu valley. The Thimphu valley, so devised, is demarcated by a dizzy eastern ridge that rises from the riverbed and a valley formation with gradually sloping topography, extending from Dechencholing and Simtokha, on the western banks of the Raidak. The north-south inclination of the hill ranges of the valley means that they are exposed to moist monsoon winds which deluge the innermost Himalayas and its bottommost valleys. Yet, the windward and leeward sides of the hill ranges have different vegetation patterns depending on the varying rainfall incidence in the two sides. Thimphu valley lying in the leeward side of the mountains is analogously dry and comprises of a different type of vegetation as related to the windward side. Hence, the coniferous vegetation in the valley is attributed to this phenomenon. Punakha, the old capital of Bhutan, is on the windward side with broad-leaved trees dominating the topography.